As disclosed in U.S. Pat. No. 4,968,962, thermal cutoffs are commonly combined with a resistance heater. In the event of a circuit malfunction, the resistance heater is energized for rapidly raising the thermal cutoff to a temperature at which it operates to provide an open circuit. U.S. Pat. No. 4,968,962, which is incorporated herein by reference in its entirety, discloses a simplified manner of mounting a thermal cutoff and for assembling the same in heat transfer relationship with a resistor.
In one arrangement, the thermal cutoff and resistor are held in physical contact one with another by a metal clip. The metal clip is formed preferably of beryllium copper to provide good heat transfer from the resistor to the thermal cutoff. The clip is generally U-shaped in an end view and includes a substantially flat base portion having a pair of curved arms extending therefrom and toward one another. The arms have a curvature that is approximately the same or slightly smaller than the curvature of the bodies of the thermal cutoff and the resistor. The arms terminate in an outwardly curved end portion to facilitate snapping one of the thermal cutoff or resistor elements into the clip once the other is already in position. The distance between the outer arms is preferably less than the combined diameters of the bodies of the thermal cutoff and the resistor. Thus the arms will be under bending stress when the thermal cutoff and resistor are received therein and will bias the thermal cutoff and resistor into firm physical engagement with each other for optimum heat transfer.
While the prior art clip functions well to hold the thermal cutoff in heat transfer relationship with the resistor, it has been found that it can be difficult to "snap" the thermal cutoff and the resistor into the clip.
The present invention overcomes the difficulty of "snapping" the thermal cutoff and the resistor into a clip by using two identical clips when each is mounted in a corresponding one-half of a housing, face each other as the housing is assembled and allows the unit to be assembled without snapping the resistor and the thermal cutoff into position. The opposing clips provide the necessary force to hold the components secure. An arcuate end is formed on the clip such that when opposing ones of the clips face each other in the housing, the arcuate ends substantially encircle one-half of one of the electrical devices, either the resistor or the thermal cutoff device. A resilient finger is formed on the other end of the clip such that when the opposing clips face each other the resilient fingers grasp the other electrical device, the thermal cutoff or the resistor, and pull it into engagement with the first electrical device for heat transfer relationship. The resilient finger deflects to allow electrical devices of different diameter to be used in the housing. In order to increase the ease of deflection of the resilient finger to accommodate various size electrical devices, at least one slot is formed in the resilient finger on the clip. Further, at least one elongated projection is attached to the metal clip for attaching the clip to the housing. Each one-half of the housing has at least one slot formed therein for receiving the corresponding elongated projection on the metal clip such that the elongated projection of each metal clip is inserted in the corresponding slot to attach a clip to each housing half. Also, a raised stop is integrally formed with each housing half such that the stop is in spaced relationship with the resilient finger of an attached clip to limit the amount the resilient finger can deflect, thereby placing a limit on the maximum size of the electrical device to be used in the electrical assembly.
Thus it is an object of the present invention to provide a device for holding a first electrical device and a second electrical device in assembled relationship to each other in a housing and biasing the devices into engagement with each other in the housing. The device is a metal clip which has one arcuate end such that when opposing ones of the clips face each other in the housing, the arcuate ends substantially encircle one-half of one of the electrical devices such as the thermal cutoff device. A resilient finger is formed on the other end of the clip such that when opposing clips face each other, the resilient fingers grasp the other electrical device such as a resistor and pull it into engagement with the thermal cutoff device for heat transfer relationship. The resilient fingers deflect to allow electrical devices of different diameter to be used in the housing.
It is also an object of the present invention to increase the ease of deflection of the resilient finger to accommodate the various size electrical devices by forming at least one slot in the resilient finger.
It is also an object of the present invention to provide at least one elongated projection attached to the metal clip for attaching the clip to the housing.
It is still another object of the present invention to provide a raised stop integrally formed with each housing half such that the stop is in spaced relationship with the resilient finger of the attached clip to limit the amount the resilient finger can deflect, thereby placing a limit on the maximum size of the electrical device to be used in the electrical assembly.
It is still another object of the present invention to provide opposing clips in a housing, to provide the necessary force to hold components in a secure manner without requiring the components to be snapped into position in the clips.